Method for the production of paper bags



2 Sheets-Sheet 1 YPIbL F LUHRMANN ETAL METHOD FOR THE PRODUCTION OF PAPER BAGS Filed Oct. 18, 1950 n Inven I'OrS 2 Sheets-Sheet 2 :1. \e. i W$53+ AfLorn EL)! 5 F LUHRMANN ErAL METHOD FOR THE PRODUCTION OF PAPER BAGS Oct. 5, 1954 Filed Oct. 18, 1950 Patented Oct. 5, 1954 lED STATES TENT QFFICE METHOD FOR THE PRODUCTION OF PAPER BAGS Fritz Liihrmann, Lengerich,

Westphalia, and

Application October 18, 1950, Serial No. 190,754

Claims priority, application Germany October 22, 1949 7 Claims.

This invention relates to new and useful improvements in the production of paper bags.

Paper bags are, as is known, manufactured by machine in the following manner, first of all tubes having a longitudinal gluing seam are produced from paper webs. These bag tubes are folded on both sides over their entire lengths. The bag tubes are then piled on top of each other and must be kept in storage until the glue of their longitudinal glued seams has attained its cementing force and no longer yields.

The ends of these bag tubes are then provided with bottoms on a bottom folding machine. A bottom is either formed at only one end of each tube and the bag tube is thus shaped into an open bag or else a bottom is placed on both ends and a valve bag is thus obtained. The known manufacture of bag bottoms begins with the opening or spreading open of the fiat bag tube ends, whereupon the folding and gluing of these spread bag tube ends into bag bottoms is effected. The opening or spreading open of the bag tube ends is effected by special equipment, for example suction devices which grasp the ends of the bag tubes on both sides and are then actuated in such a manner that they open the ends of the bag tubes for the introduction of folding plates.

Qne object of this invention is the production of paper bags in one continuous operation. This and other objects will become apparent from the following escription read in conjunction with the drawings in which:

Fig. 1 shows a piece of paper, used for the formation of a paper bag, grooved at the bag folding lines;

Fig. 2 is an end view of the piece of paper showing the direction of bend in accordance with the folding process;

Fig. 3 is a section along line A-B of Fig. 1, showing the direction of bend in accordance with folding process;

Fig. i is one form of embodiment of the grooves;

Fig. 5 is the piece of paper which is developed in a tube shape in the vicinity of the bag wall to be formed showing the spread-open bottom parts of the bag;

Fig. 6 is the paper bag with its bottom still open;

Fig. 7 is a side elevation of a device for carrying out the method, shown through section A--B of Fig. 8; and

Fig. 8 is a top elevation of the device shown in Fig. 7.

In accordance with the present invention, the piece of paper used in the formation of a paper bag is scored for folding along predetermined bag fold lines and then folded into a fiat tubular shape only where the bag wall will be formed, then the parts of the bag bottoms which due to the particular manner of folding and scoring are automatically spread open, are combined with each other to form bag bottoms.

By this new method, paper bags can be manufactured much more simply and rapidly than was heretofore known, inasmuch as now it is not necessary to first of all form a bag tube of the known kind, the gluing seam of which must be dry before the bottoms can be formed. Also, the opening of the bag tube ends, in order to form the bottom, is no longer necessary so that the complicated devices formerly used for this purpose, for example suction devices, are no longer needed. In addition to this, the bag bottom ends, in accordance with the new method, are spread apart much more uniformly than in accordance with the old method so that the finished bag bottoms are much more uniform in appearance than. those previously made, and finally the corner folds of the bag bottoms no longer receive bent lines during the formation of the bag tubes which, when produced in accordance with the known methods, appear in their center, and run parallel to the folding lines of the bottom side flaps and weaken the bag wall there and at the bag ends.

In accordance with the invention, a machine may be used for the carrying outof the method consisting of a pair of scoring rollers or several pairs of scoring rollers followed by a device for forming the bag jacket, and a subsequent device for forming the automatically spread-open bottom parts of the bag into bag bottoms.

By means of such a machine, the paper bags can be formed in a continuous uninterrupted operation from paper consisting of one or more layers.

In accordance with the present invention, by having the device for combining the spread-open bottom ends operate in a direction opposite the direction of operation of the previous device, there is obtained a machine having a shorter structural length.

Referring to Fig. 1 of the drawing, the paper 1 serving for the formation of a paper bag, is provided on both sides with both an individual longitudinal folding line 2 and a longitudinal folding line 3. Between the two folding lines 2, there extend the transverse folding lines 4. At

points 5, the transverse folding lines 4 come against the longitudinal folding lines 2. From points 5, bottom folding lines 6 branch out. All of these bag folding lines are scored in accordance with the folding process, i. e. the scored are provided in the manner that they favor the turning over of the individual bag parts in their pertinent direction of bend during the bag folding, as can be seen diagrammatically in Figs. 2 and 3.

If the piece of paper I during the scoring is pressed in, in the direction of the small straight arrow 1, the direction of bend then lies in the direction of the arc-shaped arrows E; so that the folding procedure in the direction of these arrows 8 is facilitated. During the folding of the bag,

the individual parts of the bag which are to. be folded over are easily folded over in the directions indicated by the arrows.

The form of the scores can be varied; for example, they can be developed in the manner shown. in Fig. 4 in the drawing. The form of the scores is selected to fit each individual case, depending on the strength of the piece of paper serving for the formation of the paper bag and also depending upon the nature of the material which is to be used for the manufacture of the bag. The piece of paper 4 serving for the formation of the paper bag, may consist as is known of several layers, the edges of which can be staggered with respect to each other.

The scored piece of paper i is then formed in the region of the bag wall which is to be formed into the shape of a fiat tube as can be noted from Figure of the drawing. Parts 9 and H] of the piece of paper i are only grasped in the region lying between the longitudinal folding lines 2-, folded along the transverse fold lines d and pasted together in the known manner.

By the folding of parts 9 and iii, are the bag bottom parts H produced which spread open by themselves so that it is unnecessary to open these parts by a special. operation in the formation of the bottom.

The spread bag bottom parts II can easily be combined with each other to form bag bottoms, inasmuch as it is generally not difficult to fold the bottom flaps l3 and i4 over, along the folding lines 3, even if the corner flaps are not scored along folding lines iii.

If, however, the piece of paper I serving for the formation of the paper bag is particularly difficult to bend, as for example, when it consists of several layers, it should in such cases also be scored along the folding lines l5 so that the corner flaps do not offer any appreciable re sistance to the turning over of side flaps l3 and H3. The short paths ll of folding lines 3 also need not be scored if the paper is easily folded over.

The machine for carrying out the method, which is shown in Figures '7 and 8, consists essentially of pairs of rollers for the scoring of the piece of paper, a following device for the formation of the flat tube surface and a subsequent device for the combining of the automatically spread bottom parts of the bag into the bag bottom.

The machine operates as follows:

From a supply :011, not shown in the drawing, a piece of paper i is cut in the known manner and fed to a pair of rollers !8'. Here the piece of paper I is scored along the longitudinal folding lines 2' and 3. The short paths H of folding line 3 are possibly left unscored. The scoring rolls are in such case constructed in a corresponding manner. Thereupon, the piece of paper I, pro.-

vided with the longitudinal scoring, is fed to a pair of rollers 19. The piece of paper I is now scored along the transverse. folding lines 4 and 6 and possibly also along the folding lines 16.

The piece of paper which has thus been scored is now fed to the apparatus for forming the bag jackets. Conveyor bands 20 and 2| grasp the piece of paper I and bring it against a grid 22, the front end 23 of which is obliquely situated with respect to a roller 24. Grid 22 has a transverse folding bar 25 below which the prong end 2% of the piece of paper I passes after it has been conducted obliquely upward over grid 22. Grid 22 is then turned around its pin 28 in the direction of arrow 21. It now assumes the position 29v shown in. dotted lines. The turning of grid 22 is effected via a lever system which is pivoted to pin 35 of its swinging lever 3i and is actuated from ashaft of the machine, as for example by a cam. The lever system and its actuating equipment is not shown in the drawing,

When the front end 23 of grid 22 has been turned downward, the transverse folding machine 25 folds the piece of paper I along a folding line 4- so that it assumes a bent position 31''. shown. in the drawing by dotted lines. In this folded bent position 32, the bent over end 26 of the piece of. paper l is fed: to a pair of rollers consisting of rollers 24 and. 33. These rollers 24 and 33 have recesses 34 in which the grid bars 35 of grid 22 can move when grid 22' is turned. Rollers 2/5 and 32% grasp the piece of paper I in the region of the bag wall which is to be formed but not at the ends, thus the paper is grasped only in a region lying between the longitudinal folding lines 2. The transverse folding bar 25 is no longer than the transverse folding line 4'.

The folded over end 26 of the piece of paper I is conducted by rollers 24 and 33 against a stop where it is maintained in its bent position by retainers 3?. During this folding process, the corresponding parts i E of the bag bottom have automatically been spread open.

A beater knife 38 then folds the other end of the piece of paper l along the other folding line '9. This beater or folding knife 38 is provided with levers 39 which are moved in the direction of arrow d!) by means of an actuating mechanism driven by the shaft of the machine. The actuating mechanism for folding knife 38, which engages by means of a lever system at the pin M of lever 39, is not shown in the drawing.

In accordance with this folding process, the piece of paper I is only formed into a flat tube in the region of the bag wall which is to be formed and has automatically spread bag bottom parts H the form which can be noted from Figure 5 of the drawing.

The piece of paper i is then passed in this form between rollers 33 and #2. Roller 62 is provided with a conveyor belt 43. Above conveyor belt 43, there is provided a conveyor belt 44. These conveyor belts 43' and 434i advance the prefolded piece of paper I past folding bars not shown in the drawing, so that the bottom flaps l3 and M are folded over and the spread bag tube ends I I are combined into bag bottoms 45. In order to show in Figure 3 such a bag bottom part, between conveyor belts 43 and l-i, the plate 45 between roller pairs 48 and I9 is not shown.

If it is desirable to form a bag with only one closed end, the paper need not be scored with the lines 2, 3, 5, H) and H on the end. to remain open, also the transverse folding lines 4 may be;

extended to the edge of the paper at this open end.

The same device as is used to form double bottom bags may, of course, be used to form the single bottom bag by merely folding but one end. in the form of the bottom. Similarly, the machine may be set up to score the paper as indicated for a single bottom bag.

It can thus be seen that according to the invention, paper bags are formed in one continuous operation by scoring the paper to be made into a bag along folding lines running from top to bottom of the bag to be formed, but not extending to the portion to be formed into the bag bottom, folding the paper along the said scored folding lines in the form of a flat tube so that the bottom portion remains in a substantial open position, and then folding the said open portion to form the bag bottoms.

The device used for the above method consists of means for scoring the paper in the manner indicated, means for folding the paper into a fiat tube except for the ends to become the bottom, and any known means for folding the open bottom portions together to form the bag bottoms.

Though scoring the paper along the predetermined folding line is preferred prior to folding the paper, according to the method, the paper may be prepared in any way so long as the folding takes place along the predetermined folding lines. Such folding can take place without first scoring.

We claim:

1. Method for the production of paper bags in a continuous operation from paper, such paper being in the form of a substantially rectangular sheet, comprising establishing a bag wall portion and at least one bag end portion on such paper, said bag end portion being positioned at at least one end of such paper, establishing two first folding lines on said bag wall portion of such paper terminating at the beginning of said bag end portion to leave said bag end portion free from any straight continuation thereof, said first folding lines being positioned so that the shortest distance between said first folding lines at any point is less than the sum of the shortest distances between each said first folding line and the closest respective paper edge thereto, folding such paper along said folding lines in the form of a flat tube, whereby said bag end portion remains in a substantially open position, folding said bag end portion in the form of a bag bottom, thus forming a paper bag.

2. Method according to claim 1 in which said first folding lines are established by scoring such paper.

3. Method according to claim 1 in which at least one 2nd folding line is established, said 2nd folding line being in said bag bottom portion and positioned to run at substantially right angles to said first folding lines.

4. Method according to claim 3 in which at least one pair of 3rd and 4th, and at least one pair of 5th and 6th folding lines are established, said 3rd and 4th folding lines contacting each other at an angle, of about therebetween, said contact occurrin at at least one end of one of said first folding lines, said 3rd and 4th folding lines, being positioned to contact the closest edge of such paper in the direction of said first folding line, thereby forming a substantially isosceles triangle with the said edge of such paper, said paper edge being the hypotenuse of said triangle, said 5th and 6th folding lines contacting each other at an angle of about 90 therebetween, said contact occurring at at least one of the corre sponding ends of the other of said first folding lines, said 5th and 6th folding lines being positioned to contact the same edge of such paper as said corresponding 4th and 5th folding lines, thereby forming a substantially isosceles triangle with the said edge of such paper, said edge being the hypotenuse thereof.

5. Method according to claim 4 in which there is established at least one 7th folding line, said 7th folding line passing through the entire width of the paper being positioned to fold such paper in the opposite direction to said other folding lines, and to contact both said first folding lines at the same ends thereof.

6. Method according to claim 4 including the establishing of additional folding lines positioned within said triangles at the shortest distance between the contact points of said 3rd, 4th, 5th and 6th foldin lines with said 2nd folding line, and the nearest edge of such paper, said additional folding lines being positioned to fold such paper in substantially the same direction as said 7th folding line.

7. Method according to claim 6 in which said folding lines are established by scoring such paper.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 405,590 Osborn June 18, 1889 1,368,633 Johnson Feb. 15, 1921 1,783,845 Laymon Dec. 2, 1930 1,824,383 Taylor Sept. 22, 1931 1,873,634 Potdevin Aug. 23, 1932 FOREIGN PATENTS Number Country Date 538,362 Germany of 1931 882,134 France of 1943 

